The present invention relates to a method of administration and a pharmaceutical composition containing N-acetylcysteine as the active ingredient which provide increased levels of unmodified drug in the blood following oral administration.
N-acetylcysteine (NAC) also referred to herein as unmodified NAC, (Merck Index Xth Ed., No. 82, Page 13), is used in human therapy for its mucolytic activity. It also possesses several other useful properties including expectorant activity, bronchorrheic and mucoreglatory action, ability to regulate reduced glutathione (GSH) levels, ability to stimulate immune systems debilitated by viral infections, including those debilitated by HIV virus, and its direct or indirect activity as a "free radical scavenger" that may be useful, for example, in the prevention of lung tumors.
Numerous pharmaceutical compositions containing NAC and suitable to a variety of administrative routes have been formulated, including injectable liquids, syrups, tablets, chewable tablets, soluble granulates and effervescent tablets, among others.
For prolonged treatment of several diseases, oral administration is the simplest route of administration and is the one most favored by patients. However, orally administrated NAC is partially degraded or modified in the course of uptake in the intestine and the liver, primarily by deacetylation, reducing its availability in the blood. In a number of therapeutic applications, deacetylated NAC in the bloodstream is less effective or ineffective.
Several salts of NAC, such as those with alkali metals or with basic amino acids, have been described. However, none of these products is able to increase the blood levels of unmodified NAC produced by oral administration.